Thermodynamic optimization of the binary CaO-ZnO and ternary CaO-ZnO-SiO2 systems

Liquidus phase equilibrium data of the present authors for the CaO-ZnO-SiO2 system (as a part of research program on the characterization of the multicomponent PbO-ZnO-FeO-Fe2O3-"Cu2O"-CaO-SiO2 system), combined with phase equilibrium and thermodynamic data from the literature, have been used to obtain a self consistent set of parameters of the thermodynamic models for all phases. The modified quasichemical model is used for the liquid slag phase; lime (Ca,Zn)O, zincite (Zn,Ca)O, alpha-and alpha'-dicalcium silicate (Ca,Zn)(2)SiO4 and tricalcium silicate (Ca,Zn)(3)SiO5 are described within Bragg-Williams formalism; tridymite, cristobalite SiO2, wollastonite, pseudowollastonite CaSiO3, rankinite Ca3Si2O7, willemite Zn2SiO4, melilite (hardystonite) Ca2ZnSi2O7 and Ca-Zn feldspar CaZnSi3O8 are treated as stoichiometric compounds. From these model parameters, the optimized ternary phase diagram is back calculated.